Application of liquid coating material

Abstract

A method of applying a coating composition, which preferably has a high solids content, to a workpiece. The method is one wherein a coating composition is atomized into liquid particles, an electrical charge is imparted with an induction charging electrode means on the particles substantially simultaneously with their formation, and the charged particles are directed to an electrically-receptive workpiece, and includes the improvement comprising heating the coating composition to adjust its conductivity and to enhance the induction charging of the particles formed from the heated coating composition. In a preferred embodiment, the charged particles are cooled before they reach the workpiece.

What is claimed is: 
     
       1. In the method of applying a liquid coating composition to a workpiece wherein a coating composition is atomized into liquid particles, an electrical charge is imparted with an induction charging electrode means on said particles substantially simultaneously with their formation, and the charged particles are directed to an electrically-receptive workpiece, the improvement comprising heating said coating composition to adjust its conductivity and to enhance the induction charging of the particles formed from said heated coating composition. 
     
     
       2. A method as claimed in claim 1, wherein the heated coating composition is gas-atomized. 
     
     
       3. A method as claimed in claim 2 wherein the gas employed in atomizing the coating composition is air. 
     
     
       4. A method as claimed in claim 2 wherein the gas employed in atomizing the coating composition is of a temperature to effect the cooling of the charged particles. 
     
     
       5. A method as claimed in claim 1 wherein the ambient atmosphere is of a temperature to effect the cooling of the charged particles. 
     
     
       6. A method as claimed in claim 1 wherein the coating composition is a paint composition having a solids content by weight of at least about 60 percent. 
     
     
       7. A method as claimed in claim 1 wherein the heated coating composition has an electrical conductivity of from about 0.03 μmho/cm to about 0.9 μmho/cm. 
     
     
       8. A method as claimed in claim 7 wherein the heated coating composition has a viscosity less than about 200 centipoise. 
     
     
       9. A method as claimed in claim 8 wherein the viscosity is less than about 100 centipoise. 
     
     
       10. A method as claimed in claim 1 wherein the workpiece is electrically grounded.